Inhibition Of Cell Division Research Articles

Three-dimensional coordination of cell-division site positioning in a filamentous cyanobacterium.

Bacterial cells mostly divide symmetrically. In the filamentous, multicellular cyanobacterium Anabaena, cell-division planes are aligned vertically relative to the long axis of every single cell. This observation suggests that both the placement and the angle of the division planes are controlled in every single cell so that the filament can grow in one single dimension along the long axis. In this study, we showed that inactivation of patU3 encoding a cell-division inhibitor led cells to divide asymmetrically in two dimensions leading to twisted filaments, indicating that PatU3 controls not only the position but also the angle of the division planes. Deletion of the conserved minC and minD genes affected cell division symmetry, but not the angle of the division planes. Remarkably, when both patU3 and minCD were inactivated, cells could divide asymmetrically over 360° angles in three dimensions across different cellular sections, producing not only cells with irregular sizes, but also branching filaments. This study demonstrated the existence of a system operating in a three-dimensional manner for the control of cell division in Anabaena. Such a regulation may have been evolved to accommodate multicellular behaviors, a hallmark in evolution.

Influence of varying soil moisture on growth and yield of Chia (Salvia hispanica l.) in Meru county, Kenya.

moisture content at different growth stages is unknown. A field experiment was conducted in March-June and June-October 2021 to determine the influence of different soil moisture regimes on the growth and yield of Chia. A randomized complete block design with three replications was used. Chia plants were subjected to four soil moisture regimes; (i)watering to the seedling stage (seedling), (ii) watering to the vegetative stage (vegetative), and (iii) watering to the flowering stage (flowering) (iv) continuous watering (control). High soil moisture of 89-93 %, significantly increased (p≤0.05) the vegetative growth of Chia plants. Plant height, stem diameter and number of leaves increased by 65-180%, 100-109% and 92-565%, respectively. 20-40% reduction in the available soil water to the plant decreased growth of Chia. Low soil moisture of 30-32 % caused plants to produce 172-220% less seed yield than control plants. Seasonal variation was noted, with increased vegetative growth and seed yield reported in the March-June 2021 season compared to the June-October 2021 season. Decreased vegetative growth and yields was a result from inhibition of cell enlargement or cell division under reduced soil moisture. The study recommends watering to the flowering stage as the best practice for water saving and increasing Chia production in Kenya.

Cytotoxic and antitumor properties of methionine γ-lyase conjugate in combination with S-alk(en)yl–L-cysteine sulfoxides

Background. Enzyme prodrug therapy is a promising strategy to treat solid malignancies. The utilization of two-component systems, including an enzyme and a non-toxic prodrug, to generate cytotoxic compounds directly at the surface of the tumor cell can be successful strategy in reducing the overall toxic load on the body.Aim. To determine antitumor activity of the pharmacological pair C115H methionine γ-lyase (C115H MGL) conjugated with daidzein (C115H MGL-Dz) and of S-alk(en)yl-L-cysteine sulfoxides against various types of solid tumors in vitro and in vivo.Materials. MTT-test was used to determine the cytotoxicity of C115H MGL-Dz in the presence of S-alk(en)yl-L-cysteine sulfoxides in vitro against Sw620 (colon cancer), Panc1 (pancreatic cancer), and 22Rv1 (prostate cancer). Apopto- sis induction and cell cycle alteration in 22Rv1, Sw620, and SKBR3 cell lines were studied using the Muse® Caspase-3/7 and Muse® Cell Cycle Assay kits. In vivo anticancer activity was studied on Sw620, Panc1, and 22Rv1 subcutaneous xenografts in Balb/c nude mice.Results. The C115H MGL-Dz had the maximum cytotoxic activity in the presence of S-propyl-L-cysteine sulfoxide (propiin) with IC50 values: 3.88 and 5.4 for Panc1 and 22Rv1, respectively. Dipropyl thiosulfinate formed by the β-eli-mination of propiin catalyzed by C115H MGL-Dz, induces apoptosis through both the activation of caspases and alternative pathways, and also it inhibits cell division, contributing to a decrease in the concentration of cells in the G2/M phase. The anticancer efficacy of the pharmacological pair C115H-Dz/propiin in vivo indicated a significant decrease in Panc1 tumor volume (tumor growth inhibition (TGI) 67.5 %, p = 0.004), Sw620 (TGI 22.07 %, p = 0.12) and 22Rv1 (TGI 70 %, p = 0.043).Conclusion. Pharmacological pair C115H MGL-Dz/propiin was capable of suppressing tumor development in malignant solid tumors and might be considered as a potential anticancer approach in cancer prodrug therapy.

Manipulation of topoisomerase expression inhibits cell division but not growth and reveals a distinctive promoter structure in Synechocystis

In cyanobacteria DNA supercoiling varies over the diurnal cycle and is integrated with temporal programs of transcription and replication. We manipulated DNA supercoiling in Synechocystis sp. PCC 6803 by CRISPRi-based knockdown of gyrase subunits and overexpression of topoisomerase I (TopoI). Cell division was blocked but cell growth continued in all strains. The small endogenous plasmids were only transiently relaxed, then became strongly supercoiled in the TopoI overexpression strain. Transcript abundances showed a pronounced 5'/3' gradient along transcription units, incl. the rRNA genes, in the gyrase knockdown strains. These observations are consistent with the basic tenets of the homeostasis and twin-domain models of supercoiling in bacteria. TopoI induction initially led to downregulation of G+C-rich and upregulation of A+T-rich genes. The transcriptional response quickly bifurcated into six groups which overlap with diurnally co-expressed gene groups. Each group shows distinct deviations from a common core promoter structure, where helically phased A-tracts are in phase with the transcription start site. Together, our data show that major co-expression groups (regulons) in Synechocystis all respond differentially to DNA supercoiling, and suggest to re-evaluate the long-standing question of the role of A-tracts in bacterial promoters.

Physiological conditions favorable to domoic acid production by three Pseudo-nitzschia species

Twenty-six species of the cosmopolitan genus Pseudo-nitzschia can produce domoic acid (DA), a neurotoxin responsible for amnesic shellfish poisoning (ASP). To improve knowledge on this issue, we studied the physiological conditions favorable to DA production and accumulation by three Pseudo-nitzschia species from French coastal waters: P. australis, P. pungens, and P. fraudulenta. They were grown in batch cultures under silicate limitation to characterize their physiological traits and calculate their DA production rates. Three strains were studied per species to consider intraspecific diversity and better characterize interspecific differences. DA production was not influenced by growth or silicate limitation in any of the three species. In contrast, silicate limitation in the stationary phase led to DA accumulation by inhibiting cell division, while DA production was still active. The maximum cellular DA (cDA) production rate was 2.95 pg cell−1 d−1 for P. australis, 0.07 pg cell−1 d−1 for P. pungens, and 0.03 pg cell−1 d−1 for P. fraudulenta. The physiological conditions favorable to cDA production and accumulation by P. australis and P. pungens differed. The three species presented similar growth rates, but P. australis had higher photosynthetic capacities that could partly explain its higher DA production potential. The cDA production and the net dissolved DA (dDA) production in the culture medium were favored by different growth conditions. The cDA production to net dDA production ratio was species specific, with P. pungens excreting proportionally more of its produced DA. These laboratory results on cultures imply that cDA production and net dDA production can occur during all phases of P. australis, P. pungens, and P. fraudulenta blooms. The interactions between the species composition of the bloom, the species-specific capacity for DA production, and the effect of silicate limitation – among other factors – on DA cell quotas drive the toxigenicity of Pseudo-nitzschia blooms.

In Vitro Selection of Enterobacter cloacae with Cefepime, Meropenem, and Ceftazidime-Avibactam Generates Diverse Resistance Mechanisms

Five Enterobacter cloacae isolates were subjected to 10-day serial passage in broth microdilution with cefepime, meropenem, or ceftazidime-avibactam to evaluate increases in minimum inhibitory concentration (MIC) and resistance mechanisms after exposure. Post-exposure isolates displaying >2-fold changes from the parent isolate were analysed alongside the parent isolate. Increases in MIC were 4- to 256-fold (median: 16-fold) after cefepime exposure, 16- to 128-fold (64-fold) after meropenem, and 2- to 32-fold (8-fold) after ceftazidime-avibactam. Post-exposure isolates had diverse mechanisms, identified using a combination of short and long whole-genome sequencing. All agents selected for AmpC alterations in one isolate set. OmpC and TetA/AcrR regulator alterations were noted in meropenem and ceftazidime-avibactam post-exposure isolates of the same set. Other mutations in AmpC were noted when isolates were exposed to cefepime or ceftazidime-avibactam. A premature stop codon in the cell division inhibitor protein, MioC was observed when one parent isolate was exposed to any of the agents, indicating a cell persistence mechanism. Mutations in less common transporter systems and protein synthesis components were also noted. All agents showed cross-resistance to other β-lactams and resistance mechanisms were diverse, with some not usually associated with β-lactam resistance in Enterobacterales. This initial evaluation indicates that cefepime and meropenem select for isolates with higher MIC values compared to ceftazidime-avibactam. Further studies evaluating these findings should be performed for other species for which the primary β-lactam resistance mechanism is not gene acquisition. These studies should evaluate these observations in vivo to assess their translation into patient treatment policies.

Lactate-dependent chaperone-mediated autophagy induces oscillatory HIF-1α activity promoting proliferation of hypoxic cells.

Response to hypoxia is a highly regulated process, but little is known about single-cell responses to hypoxic conditions. Using fluorescent reporters of hypoxia response factor-1α (HIF-1α) activity in various cancer cell lines and patient-derived cancer cells, we show that hypoxic responses in individual cancer cells can be highly dynamic and variable. These responses fall into three classes, including oscillatory activity. We identify a molecular mechanism that can account for all three response classes, implicating reactive-oxygen-species-dependent chaperone-mediated autophagy of HIF-1α in a subset of cells. Furthermore, we show that oscillatory response is modulated by the abundance of extracellular lactate in a quorum-sensing-like mechanism. We show that oscillatory HIF-1α activity rescues hypoxia-mediated inhibition of cell division and causes broad suppression of genes downregulated in cancers and activation of genes upregulated in many cancers, suggesting a mechanism for aggressive growth in a subset of hypoxic tumor cells.

Plasmids Can Shift Bacterial Morphological Response against Antibiotic Stress.

Bacterial cell filamentation is a morphological change wherein cell division is blocked, which can improve bacterial survival under unfavorable conditions (e.g., antibiotic stress that causes DNA damage). As an extrachromosomal DNA molecule, plasmids can confer additionally advantageous traits including antibiotic resistance on the host. However, little is known about whether plasmids could shift bacterial morphological responses to antibiotic stress. Here, it is reported that plasmid-free cells, rather than plasmid-bearing cells, exhibit filamentation and asymmetrical cell division under exposure to sub-inhibitory concentrations of antibiotics (ciprofloxacin and cephalexin). The underlying mechanism is revealed by investigating DNA damage, cell division inhibitor sulA, the SOS response, toxin-antitoxin module (parDE) located on plasmids, and efflux pumps. Significantly higher expression of sulA is observed in plasmid-free cells, compared to plasmid-bearing cells. Plasmid carriage enables the hosts to suffer less DNA damage, exhibit stronger efflux pump activities, and thus have a higher antibiotic tolerance. These benefits are attributed to the parDE module that mediates stress responses from plasmid-bearing cells and mainly contributes to cell morphological changes. Collectively, the findings demonstrate that plasmids can confer additional innate defenses on the host to antibiotics, thus advancing the understanding of how plasmids affect bacterial evolution in hostile environments.

Dissection of Functional Domains of Orc1-2, the Archaeal Global DNA Damage-Responsive Regulator

Orc1-2 is a non-initiator ortholog of archaeal/eukaryotic Orc1 proteins, which functions as a global regulator in DNA damage-responsive (DDR) expression. As for Orc1 initiators, the DDR regulator harbors an AAA+ ATPase domain, an Initiator-Specific Motif (ISM) and a winged-helix (wH) DNA-binding domain, which are also organized in a similar fashion. To investigate how Orc1-2 mediates the DDR regulation, the orc1-2 mutants inactivating each of these functional domains were constructed with Saccharolobus islandicus and genetically characterized. We found that disruption of each functional domain completely abolished the DDR regulation in these orc1-2 mutants. Strikingly, inactivation of ATP hydrolysis of Orc1-2 rendered an inviable mutant. However, the cell lethality can be suppressed by the deficiency of the DNA binding in the same protein, and it occurs independent of any DNA damage signal. Mutant Orc1-2 proteins were then obtained and investigated for DNA-binding in vitro. This revealed that both the AAA+ ATPase and the wH domains are involved in DNA-binding, where ISM and R381R383 in wH are responsible for specific DNA binding. We further show that Orc1-2 regulation occurs in two distinct steps: (a) eliciting cell division inhibition at a low Orc1-2 content, and this regulation is switched on by ATP binding and turned off by ATP hydrolysis; any failure in turning off the regulation leads to growth inhibition and cell death; (b) activation of the expression of DDR gene encoding DNA repair proteins at an elevated level of Orc1-2.

RAD6 inhibition enhances paclitaxel sensitivity of triple negative breast cancer cells by aggravating mitotic spindle damage

BackgroundPaclitaxel (PTX), a first-line therapy for triple negative breast cancers (TNBC) induces anti-tumor activity by microtubule stabilization and inhibition of cell division. Its dose-limiting toxicity and short half-life, however, pose clinical challenges underscoring the need for strategies that increase its efficiency. RAD6, a E2 ubiquitin conjugating enzyme, is associated with centrosomes at all phases of cell cycle. Constitutive overexpression of the RAD6B homolog in normal breast cells induces centrosome amplification and multipolar spindle formation, indicating its importance in centrosome regulation.MethodsTNBC centrosome numbers were scored by pericentrin immunostaining. PTX sensitivities and interactions with SMI#9, a RAD6-selective small molecule inhibitor, on TNBC cell survival were analyzed by MTT and colony forming assays and an isogenic MDA-MB-468 TNBC model of PTX resistance. The molecular mechanisms underlying PTX and SMI#9 induced cytotoxicity were determined by flow cytometry, immunoblot analysis of cyclin B1 and microtubule associated protein TAU, and dual immunofluorescence staining of TAU and α-tubulin.ResultsOur data show aberrant centrosome numbers and that PTX sensitivities are not correlated with TNBC BRCA1 status. Combining PTX with SMI#9 synergistically enhances PTX sensitivities of BRCA1 wild-type and mutant TNBC cells. Whereas SMI#9/PTX combination treatment increased cyclin B1 levels in MDA-MB-468 cells, it induced cyclin B1 loss in HCC1937 cells with accumulation of reproductively dead giant cells, a characteristic of mitotic catastrophe. Cell cycle analysis revealed drug-induced accumulation of tetraploid cells in S and G2/M phases, and robust increases in cells with 4 N DNA content in HCC1937 cells. TAU overexpression is associated with reduced PTX efficacy. Among the six TAU isoforms, both SMI#9 and PTX downregulated 1N3R TAU in MDA-MB-468 and HCC1937 cells, suggesting a common mechanism of 1N3R regulation. Dual TAU and α-tubulin immunostaining showed that SMI#9 induces monopolar mitotic spindles. Using the isogenic model of PTX resistance, we show that SMI#9 treatment restores PTX sensitivity.ConclusionsThese data support a common mechanism of microtubule regulation by SMI#9 and PTX and suggest that combining PTX with RAD6 inhibitor may be beneficial for increasing TNBC sensitivities to PTX and alleviating toxicity. This study demonstrates a new role for RAD6 in regulating microtubule dynamics.

P16 and P21 are involved in the pathogenesis of endometrial thinning: A cross-sectional study.

P16 plays a role in the negative regulation of cell proliferation, regulating cell apoptosis to control the growth of tumor cells. P21 is a nuclear protein that suppresses DNA synthesis and inhibits cell division. This study aimed to examine the expression and roles of P16 and P21 in endometrial thinning. Thirty cases of endometrial biopsy diagnosed as endometrial thinning were assessed by p16 and p21 immunohistochemistry from March 2014 to August 2020 in Huazhong University of Science and Technology Union Shenzhen Hospital. Another thirty cases of normal endometrium in the same period were assessed as controls. The specimens underwent histological analysis, and P16 and P21 were assessed by immunohistochemistry. There were no statistically significant differences in age, menstrual cycle, BMI, sex hormone levels, gravidity and parity between the two groups (all P > .05). In the endometrial thinning group, P16 was expressed in the endometrial adenoid nucleus, cytolymph and interstitial cell nucleus. In the normal group, P16 was mainly expressed in the endometrial adenoid nucleus, with some P16 signals detected in the endometrial interstitial nucleus. P21 expression was mainly detected in the endometrial adenoid nucleus. P16 and P21 amounts in endometrial thinning cases were significantly lower than those of the normal endometrial group. There was no correlation between p16 and p21 amounts. This study revealed aberrant expression of P16 and P21 in the endometrium might be due to a compensatory effect of the thin endometrium to increase cell proliferation and suppress cell apoptosis. However, the pathological roles of P16 and P21 in endometrial thinning and the contribution of cell senescence deserve further investigation.

Timing of Postfertilization Pressure Shock Treatment for the Production of Mitotic Gynogens in Six Salmonid Species

AbstractDoubled haploid gynogens are individuals whose genetic material consists of two identical maternal chromosome sets and who lack paternal genetic contributions. These individuals can be useful in whole‐genome sequence assembly to eliminate allelic variation in an individual that otherwise complicates the discrimination of SNPs and paralogs in regular diploids. This is particularly important in salmonid species, which have extensive remnants of an ancestral whole‐genome duplication. Further, doubled haploid individuals are fully homozygous and can be used to generate clonal lines. Here, successful timing was determined for late pressure shocking for producing doubled haploid gynogens in five Oncorhynchus species (Chinook Salmon O. tshawytscha, Coho Salmon O. kisutch, Chum Salmon O. keta, Pink Salmon O. gorbuscha, and Sockeye Salmon O. nerka) and one Salvelinus species (domesticated Artic Char Salvelinus alpinus). For this study, sperm was treated with UV irradiation to inactivate the paternal nuclear DNA and used to fertilize eggs. The resulting zygotes were pressure shocked at various times following fertilization to form doubled haploid embryos via inhibition of the first cell division (mitotic gynogenesis). At an incubation temperature of 10.5°C, successful postfertilization pressure shock times for maximal survival of confirmed gynogens were 2.41–2.83 accumulated thermal units (ATUs) for Coho Salmon, 2.63–2.84 ATUs for Chum Salmon, 2.84–3.06 ATUs for Pink Salmon, 2.19 ATUs for Sockeye Salmon, and 2.63–3.06 ATUs for Chinook Salmon, whereas for Arctic Char a shock time of 2.29–2.54 ATUs at 4°C incubation was successful. Survival to fry stage ranged from less than 1% to 11.7%. Survivors were genotyped using microsatellite markers to assess nonpaternity and maternal homozygosity and were found to be 92.5% gynogens when averaged across all treatments and species. Mitotic gynogenetic individuals were produced in all six salmonid species and were used in subsequent studies to generate whole‐genome sequences for Chinook, Coho, Chum, and Sockeye salmons.

In Silico Modeling Study of Curcumin Diffusion and Cellular Growth

Curcumin can enhance cutaneous wound healing by improving fibroblast proliferation. However, its therapeutic properties are dose-dependent: high concentrations produce cytotoxic effects, whereas low concentrations benefit cell proliferation. Similarly, the type of administration and its moderation are key aspects, as an erroneous distribution may result in null or noxious activity to the organism. In silico models for curcumin diffusion work as predictive tools for evaluating curcumin’s cytotoxic effects and establishing therapeutic windows. A 2D fibroblast culture growth model was created based on a model developed by Gérard and Goldbeter. Similarly, a curcumin diffusion model was developed by adjusting experimental release values obtained from Aguilar-Rabiela et al. and fitted to Korsmeyer–Peppas and Peleg’s hyperbolic models. The release of six key curcumin concentrations was achieved. Both models were integrated using Morpheus software, and a scratch-wound assay simulated curcumin’s dose-dependent effects on wound healing. The most beneficial effect was achieved at 0.25 μM, which exhibited the lowest cell-division period, the highest confluence (~60% for both release models, 447 initial cells), and the highest final cell population. The least beneficial effect was found at 20 μM, which inhibited cell division and achieved the lowest confluence (~34.30% for both release models, 447 initial cells). Confluence was shown to decrease as curcumin concentration increased, since higher concentrations of curcumin have inhibitory and cytotoxic effects.

Optimization of the extraction of bioactive compounds from Muntingia calabura peels and cytotoxic and antiproliferative evaluation by the Allium cepa test

AbstractObjective and MethodsThe purpose of this article was to compare the extraction efficiency of bioactive compounds from Muntingia calabura peel using conventional methodology and ultrasound assistance, in addition, to verify the best extraction conditions, varying the drying temperature of the peels, time and solvents, and then to verify the cytotoxic and antiproliferative action of M. calabura extracts by Allium cepa.Results and ConclusionsIt was verified through the analysis of total phenolic compounds, 2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonic acid (ABTS) and iron reduction capacity that the best conditions were ultrasonic extraction, with a temperature of 50 °C, 50% aqueous ethanol solution and extraction time of 60 min. Regarding the quantification of total phenolic compounds (TPC), ABTS and ferric reducing antioxidant power (FRAP) in calabura peel, there was a variation of 571.33–1444.67 mg GAE (gallic acid equivalents) 100 g−1 dry peel for TPC, 19.36–115.74 mg Trolox 100 g−1 for ABTS and 306.73–1608.97 for FRAP. Regarding the cytotoxic effect on root growth of A. cepa, it was found that both conventional and ultrasound‐assisted extraction had an effect on onion root growth. In addition, together with the results of the analyzed cells and the literature, it can be verified that M. calabura peels also have an antiproliferative effect. This effect is due to the high concentration of phenolic compounds found in the analyzed extracts; such bioactive compounds are responsible for inhibiting cell division in meristematic cells. © 2022 Society of Chemical Industry (SCI).

Cholecystokinin Receptor Antagonist Suppresses Melanoma Growth by Inducing Apoptosis of Tumor Cells

Melanoma is a malignant skin tumor with high metastatic activity. Although melanoma has been well-studied, its cellular kinetics remain elusive. The cholecystokinin (CCK) receptor is expressed in various types of tumors because CCK promotes the survival and proliferation of tumor cells. Thus, we hypothesized that the growth of melanoma was positively regulated by signals from the CCK receptor and sought to investigate whether CCK receptor antagonists affect the growth of melanoma cells expressing CCK receptor. Immunohistochemically, the CCK receptor A is expressed in the clinical specimens of melanoma. CCK receptor antagonists decreased the viability of melanoma cells by suppressing cell division and promoting apoptosis. CCK receptor antagonists also decreased the mitochondrial membrane potential through enhanced gene expression of the proapoptotic protein, Bcl2-associated X, and tumor suppressor, p53, suggesting that the antagonist induced the apoptosis of melanoma cells in a mitochondria-dependent manner. In addition, a caspase 3 inhibitor, Z-DEVD-FMK, partially blocked the antiviability of the antagonist, indicating that caspase 3 is involved in antagonist-induced apoptosis. Notably, tumor growth was attenuated when a CCK receptor antagonist was locally administered to the melanoma-bearing mice. Therefore, our study suggests the therapeutic potential of CCK receptor antagonists in the treatment of skin cancer.

Cinnamaldehyde derivatives act as antimicrobial agents against Acinetobacter baumannii through the inhibition of cell division.

Acinetobacter baumannii is a pathogen with high intrinsic antimicrobial resistance while multidrug resistant (MDR) and extensively drug resistant (XDR) strains of this pathogen are emerging. Treatment options for infections by these strains are very limited, hence new therapies are urgently needed. The bacterial cell division protein, FtsZ, is a promising drug target for the development of novel antimicrobial agents. We have previously reported limited activity of cinnamaldehyde analogs against Escherichia coli. In this study, we have determined the antimicrobial activity of six cinnamaldehyde analogs for antimicrobial activity against A. baumannii. Microscopic analysis was performed to determine if the compounds inhibit cell division. The on-target effect of the compounds was assessed by analyzing their effect on polymerization and on the GTPase activity of purified FtsZ from A. baumannii. In silico docking was used to assess the binding of cinnamaldehyde analogs. Finally, in vivo and in vitro safety assays were performed. All six compounds displayed antibacterial activity against the critical priority pathogen A. baumannii, with 4-bromophenyl-substituted 4 displaying the most potent antimicrobial activity (MIC 32 μg/mL). Bioactivity was significantly increased in the presence of an efflux pump inhibitor for A. baumannii ATCC 19606 (up to 32-fold) and significantly, for extensively drug resistant UW 5075 (greater than 4-fold), suggesting that efflux contributes to the intrinsic resistance of A. baumannii against these agents. The compounds inhibited cell division in A. baumannii as observed by the elongated phenotype and targeted the FtsZ protein as seen from the inhibition of polymerization and GTPase activity. In silico docking predicted that the compounds bind in the interdomain cleft adjacent to the H7 core helix. Di-chlorinated 6 was devoid of hemolytic activity and cytotoxicity against mammalian cells in vitro, as well as adverse activity in a Caenorhabditis elegans nematode model in vivo. Together, these findings present halogenated analogs 4 and 6 as promising candidates for further development as antimicrobial agents aimed at combating A. baumannii. This is also the first report of FtsZ-targeting compounds with activity against an XDR A. baumannii strain.

Discovery of Epipodophyllotoxin-Derived B2 as Promising XooFtsZ Inhibitor for Controlling Bacterial Cell Division: Structure-Based Virtual Screening, Synthesis, and SAR Study.

The emergence of phytopathogenic bacteria resistant to antibacterial agents has rendered previously manageable plant diseases intractable, highlighting the need for safe and environmentally responsible agrochemicals. Inhibition of bacterial cell division by targeting bacterial cell division protein FtsZ has been proposed as a promising strategy for developing novel antibacterial agents. We previously identified 4′-demethylepipodophyllotoxin (DMEP), a naturally occurring substance isolated from the barberry species Dysosma versipellis, as a novel chemical scaffold for the development of inhibitors of FtsZ from the rice blight pathogen Xanthomonas oryzae pv. oryzae (Xoo). Therefore, constructing structure−activity relationship (SAR) studies of DMEP is indispensable for new agrochemical discovery. In this study, we performed a structure−activity relationship (SAR) study of DMEP derivatives as potential XooFtsZ inhibitors through introducing the structure-based virtual screening (SBVS) approach and various biochemical methods. Notably, prepared compound B2, a 4′-acyloxy DMEP analog, had a 50% inhibitory concentration of 159.4 µM for inhibition of recombinant XooFtsZ GTPase, which was lower than that of the parent DMEP (278.0 µM). Compound B2 potently inhibited Xoo growth in vitro (minimum inhibitory concentration 153 mg L−1) and had 54.9% and 48.4% curative and protective control efficiencies against rice blight in vivo. Moreover, compound B2 also showed low toxicity for non-target organisms, including rice plant and mammalian cell. Given these interesting results, we provide a novel strategy to discover and optimize promising bactericidal compounds for the management of plant bacterial diseases.

Lipophilic NO-Driven Nanomotors as Drug Balloon Coating for the Treatment of Atherosclerosis.

Drug-coated balloons (DCB) intervention is an important approach for the treatment of atherosclerosis (AS). However, this therapeutic approach has the drawbacks of poor drug retention and penetration at the lesion site. Here, a lipophilic drug-loaded nanomotor as a modified balloon coating for the treatment of AS is reported. First, a lipophilic nanomotor PMA-TPP/PTX loaded with drug PTX and lipophilic triphenylphosphine (TPP) compounds is synthesized. The PMA-TPP/PTX nanomotors use nitric oxide (NO) as the driving force, which is produced from the reaction between arginine on the motor substrate and excess reactive oxygen species (ROS) and inducible nitric oxide synthase (iNOS) in the AS microenvironment. The final in vitro and in vivo experimental results confirm that the introduction of the lipophilic drug-loaded nanomotor technology can greatly enhance the drug retention and permeability in atherosclerotic lesions. In particular, NO can also play an anti-AS role in improving endothelial cell function and reducing oxidative stress. The chemotherapeutic drug PTX loaded onto the nanomotors can inhibit cell division and proliferation, thereby exerting the effect of inhibiting vascular intimal hyperplasia, which is helpful for the multiple therapies of AS. Using nanomotor technology to solve cardiovascular diseases may be a promising research direction.

MraZ Transcriptionally Controls the Critical Level of FtsL Required for Focusing Z-Rings and Kickstarting Septation in Bacillus subtilis.

The bacterial division and cell wall (dcw) cluster is a highly conserved region of the genome which encodes several essential cell division factors, including the central divisome protein FtsZ. Understanding the regulation of this region is key to our overall understanding of the division process. mraZ is found at the 5' end of the dcw cluster, and previous studies have described MraZ as a sequence-specific DNA binding protein. In this article, we investigate MraZ to elucidate its role in Bacillus subtilis. Through our investigation, we demonstrate that increased levels of MraZ result in lethal filamentation due to repression of its own operon (mraZ-mraW-ftsL-pbpB). We observed rescue of filamentation upon decoupling ftsL expression, but not other genes in the operon, from MraZ control. Our data suggest that regulation of the mra operon may be an alternative way for cells to quickly arrest cytokinesis, potentially during entry into the stationary phase and in the event of DNA replication arrest. Furthermore, through time-lapse microscopy, we were able to identify that overexpression of mraZ or depletion of FtsL results in decondensation of the FtsZ ring (Z-ring). Using fluorescent d-amino acid labeling, we also observed that coordinated peptidoglycan insertion at the division site is dysregulated in the absence of FtsL. Thus, we reveal that the precise role of FtsL is in Z-ring maturation and focusing septal peptidoglycan synthesis. IMPORTANCE MraZ is a highly conserved protein found in a diverse range of bacteria, including genome-reduced Mycoplasma. We investigated the role of MraZ in Bacillus subtilis and found that overproduction of MraZ is toxic due to cell division inhibition. Upon further analysis, we observed that MraZ is a repressor of its own operon, which includes genes that encode the essential cell division factors FtsL and PBP2B. We noted that decoupling of ftsL alone was sufficient to abolish MraZ-mediated cell division inhibition. Using time-lapse microscopy, we showed that under conditions where the FtsL level is depleted, the cell division machinery is unable to initiate cytokinesis. Thus, our results pinpoint that the precise role of FtsL is in concentrating septal cell wall synthesis to facilitate cell division.

Erratum for Barnes et al., "Inhibition of Sulfate Reduction and Cell Division by Desulfovibrio desulfuricans Coated in Palladium Metal".

Erratum for Barnes et al., "Inhibition of Sulfate Reduction and Cell Division by Desulfovibrio desulfuricans Coated in Palladium Metal".